This invention relates to an automatic mail processing apparatus capable of performing sorting and piling, pick up, labeling, bundling and any other steps necessary for mail processing in an automatic sequence, and in particular, an automatic mail processing apparatus having reject means for rejecting defective mail.
Automatic mail processing apparatuses have recently been developed which incorporate a reading and sorting machine with automatic delivery, a labeling machine and a bundling machine coupled together by means of a transfer unit in an attempt to process a great amount of mail quickly and reliably with less manpower.
The reading and sorting machine reads out postal codes of the individual pieces of mail fed thereto, stores the read-out data in a memory, piles the mail in a selected one of more than one hundred sorting boxes and autmatically delivers mail from the sorting boxes to a transfer unit when a predetermined number of pieces are piled in one particular sorting box. The transfer unit transports the delivered pile of mail to a labeling apparatus, and then to a bundling apparatus. The labeling apparatus prints a bar code on a paper sheet to make a label, this bar code corresponding to sorting data (postal code, etc.) shifted in said memory in synchronism with the transportation of the mail pile, and attaches the label to the mail pile. The bundling apparatus bundles the labelled pile of mail with a crossing tape. The bundled mail is sorted by the bar codes printed on the attached labels and collected into the corresponding mailbags.
However, such conventional automatic mail processing apparatuses have the drawback that sorting data in the memory are likely to be lost by triboelectric noise generated by friction between contiguous pieces of mail in the pile while being transported from the sorting box to the labeling apparatus. If this happens, the labeling apparatus, and hence, the entire mail sorting system becomes inoperative, thus reducing the efficiency of the mail processing operation.
The bundling apparatus is required to impart a proper tension to a bundling tape so that a pile of mail is prevented from becoming unbound in the course of transportation in the bundling apparatus. On the other hand, such a bundling tape has the drawback that its tension may often be greater than the lateral strength of the mail pile, eventually rolling, or in extreme cases, breaking pieces of mail, even if the pile contains an excess number of pieces. To cope with this drawback, the number of pieces in a pile is counted at the time of sorting and the count data produced are stored in the memory together with the sorting data. When a pile of mail arriving at the bundling apparatus is determined on a basis of the count data in the memory to contain less than a determined number of pieces, that mail pile can be rejected from the conveying unit on the assumption that such a pile does not have satisfactory rigidity, so that damage by the bundling apparatus can be avoided. If the data are lost from the memory in the above-mentioned process, however, the count data are also lost, so that the number of pieces of mail cannot be determined, thus increasing the probability of damaging the mail in the bundling apparatus.
Further, even if the count data are maintained in the memory, the bundling apparatus cannot avoid the following drawback. Comparing piles of 10 postcards and 10 5 mm-thick letters, the latter has a greater rigidity than the former. When the above-mentioned threshold number is set on the basis of a less-rigid mail pile, there is the possibility that a pile having less than the predetermined threshold number of pieces, but having a good rigidity for bundling may be rejected, thus reducing the efficiency of the mail processing operation.